The bike that started the four-stroke revolution benefits from significant chassis and engine refinements, providing improved power delivery, handling and the edge that can keep you on the podium.

In 2006, Yamaha introduced a completely new YZ450F with a new engine and a new aluminum frame.

For 2007, the designers have put the YZ450F under the microscope to find more areas of improvement. The result is a revised exhaust cam, as well as revised carb and exhaust systems. The work didn’t stop there. Attention was also focused on the chassis, suspension and brakes. Numerous components were redesigned to decrease weight and the rear suspension was optimized too. The result is simple … more power, reduced weight and incredible suspension performance.

FEATURES:

– Revised liquid-cooled, 449cc, DOHC, 5-valve, 4-stroke, single with titanium valves delivers a broad power curve with a great over-rev capacity. Numerous improvements provide more low to mid rpm power and an improvement in overall powerful feeling.

– Automatic decompression system ensures easy starts in any gear with no manual lever to fuss with.

– Special intake port shape increases the velocity of the incoming charge for more complete cylinder filling and more power.

– Revised intake and exhaust camshafts feature a change in the “event angle” for improved power. The exhaust cam timing has also been changed from 105 to 100 degrees.

– Cylinder inclination angle was optimized in 2006 to centralize mass and bring the center of gravity closer to the rider for improved weight distribution and lighter handling.

– The cylinder features a ceramic composite coating which insures faster uniform heat dissipation, reduced friction and a longer service life. The outer cylinder coating has been revised for an improved appearance and easier cleaning.

– Special cylinder design features cutaways that allow the air “trapped” under the piston to enter a side chamber (or cutaway) to reduce horsepower-robbing “pumping losses.”

– The crankcase also utilizes cutaways to reduce “pumping losses.” The crankcase cutaways match the cutaways in the cylinder.

– Piston oil cooler utilizes a pinpoint nozzle that directs oil to the desired portion of the cylinder and piston, to reduce piston, cylinder and rod temperatures for improved durability.

– Oil volume in engine has been optimized to reduce weight and oil drag related power losses.

– Revised balancer shaft reduces vibration for improved rider comfort and less rider fatigue. The balancer weights have been revised to provide the rider with a better sense of rpm feeling and an improved power feeling. The lighter balancer also helps to reduce weight

– Special crankcase design features an integrated oil tank inside the cases to supply oil to the dry sump lubrication system. This design concentrates mass lower in the frame for optimum handling and lighter weight feeling. There are no exterior oil lines with this design.

– The crankcase features a tri-axis design layout for the crank, main and drive axles. This tri-axis design keeps the crankcases more compact while also centralizing mass for better handling. All of the shafts are positioned low in the cases to maintain a low centre of gravity.

– Revised clutch assembly feature a new, more rigid clutch pressure plate to improve partial clutch feeling and help reduce heat build up in the clutch. There is also a change to number of plates to lighten the clutch lever feel / pull.

– Revised CD ignition system delivers ultra-precise spark and optimized timing for faster, stronger engine response during hard acceleration, and less kickback during starting. The settings have been revised to accentuate the engine and exhaust improvements.

– Ignition coil is integrated into the spark plug cap to reduce weight and complexity.

– Revised compact, lightweight, single core, dual radiators provide outstanding cooling efficiency. A new reinforcing bar has been added to the rads for improved protection in the event of a tip over. The louvers that direct the air into the rads has been revised for improved air flow into the rads.

– Revised lightweight aluminum / stainless steel muffler not only reduces weight but improves low to mid power as well as reducing noise levels to comply with the 2007 AMA noise limit of 99dba.

– Compact aluminum semi-double-cradle frame features a cast steering head while the remainder of the frame uses forged, pipe stock and extruded components. Yamaha has maintained the semi double cradle design to allow for “controlled flex” to optimize suspension action. This frame design provides a lower centre of gravity for a light feel and razor sharp handling, plus less rider fatigue, and excellent stability.

– Revised, removable rear subframe is constructed of square-section, lightweight aluminum pipe and is now 15 grams lighter than last year with the addition of weight reducing holes. Detachable design allows easy access when servicing rear suspension components. The bolts that secure the subframe are now 10mm for easier servicing (same size as the side covers).

– Revised lightweight, tapered, aluminum swingarm is produced using “hydro forming”, a special forming method that uses high pressure water to form shapes. The revised swingarm features a change to the chain adjuster area of the arm to reduce weight. The swingarm improves overall chassis balance for a lighter handling feel.

– New, forged aluminum upper triple clamp reduces weight by 17% over last year’s cast version. The reinforcing ribs have also been modified for improved strength and reduced weight. The handlebar holder has also been revised for reduced weight.

– New forged aluminum lower triple clamp reduces weight and features a change to the reinforcing ribs. The pinch bolts have also been shortened to reduce weight.

– New Pro Taper handlebars are 8mm taller and feature a new “bend” for a roomier riding position. The Pro Taper design provides excellent strength and durability. Foam handlebar pad is included.

– 48mm, adjustable, inverted, Kayaba cartridge forks feature a twin-chamber design. The twin chamber design means the damper unit is in a separate structure which prevents aerated fork oil from entering the inner damper assembly and degrading its damping abilities. Since the inner damper is pressurized, it also eliminates bubbles forming in the oil.

– The balance between the inner and outer tubes has been optimized, while the Kashima coating on the pressure tank and the piston rod reduce friction for smoother suspension performance. The cylinder diameter is 24mm for excellent primary cushioning and a low friction oil seal is used to reduce stiction.

– The 48mm inverted KYB fork also features a Transfer Control Valve (TCV). The TCV enhances the damping force of the inner damper from mid stroke to full stroke and improves bottoming characteristics. The benefit of TCV is more precise control throughout the full stroke range. The TCV is located on the upside of the spring and its function is controlled by piston speed, not piston position … hence the term “Speed Sensitive fork”.

– “Kashima coating” has been applied to the fork tubes to reduce friction for smoother suspension performance. Front wheel travel is 300mm (11.8″).

– The shock body is 1.5mm longer than last year to optimize the ride height for more precise cornering. Selected shock body components such as the compression and damping adjuster mechanisms and spring guide have been changed from steel to aluminum to reduce weight. The piston rod diameter is 18mm while Kashima coating is used in the shock body and sub tank to reduce friction and improve suspension performance during a long moto. The rear suspension settings have been revised for 2007.

– New XXX 245mm rear disc brake features a new lighter “wave-type” rotor. This new rotor is squeezed by a single piston caliper which features an integrated master cylinder (fluid reservoir is integrated into the top of the master cylinder) for strong stopping power with excellent feel and control.

– The rear caliper and the lower portion of the wave rotor are protected by heavy duty plastic protectors.

– “Slim line” body components include: front and rear fenders, rad shrouds, side covers /number plates, gas tank and seat. This body design not only provides an aggressive appearance to the YZ450F but also allows for fast, easy rider movements.

– All new chain guide / support reduces weight for a lighter feel. Newly designed rubber swingarm protector

– Specially designed “Sun Star” rear sprocket increases the contact area between the sprocket and chain rollers, thereby reducing the load on the chain and increasing the service life of both chain and sprocket.

– Revised “flat-design” seat features a dual foam design that provides good initial softness / comfort and then increases the firmness as more pressure is applied. For 2007 a new base layer of lightweight polypropylene foam is used. The “pebble” or “gripper” finish on the top and side surfaces provides excellent rider grip and durability.